In HIV and other retroviruses the enzyme reverse transcriptase (RT) catalyzes the conversion of approximately 10kb of viral ssRNA into proviral dsDNA. Although reverse transcription can be carried out in vitro using only purified RT and primer-template, the conversion of the entire viral RNA from HIV into dsDNA in vitro has remained elusive. The broad goal of this project is to determine what additional factors may be necessary to duplicate the efficiency of reverse transcription that is observed in vivo. The viral RNA of HIV-1 is packaged into the virion in a structure known as the "core particle". Shortly after fusion of the virion with the infected cell the core particle undergoes a structural change which is visible under EM. The exact nature of the transition from core particle to actively replicating complex is largely unknown. A further goal of this project is to determine the composition of the early replicating complex in HIV and determine how this complex may change during the process of reverse transcription. Using detergent solubilized HIV virions we will perform a varation of the classical endogenous reaction to isolate actively replicating complexes and determine the protein composition and physical nature of the complexes. In addition, we will determine the roles that other viral and host proteins may play in the process of reverse transcription. Any specific viral or cellular factors identified will then be further characterized using a combination of in vitro assays and biochemical and genetic assays to identify key protein-protein interactions and their significance to efficient reverse transcription.